BMW E30 heater not heating or blower not working
Why does the E30 heater not heat or blow only lukewarm air?
Common causes are air trapped in the heater core, heater core hoses connected the wrong way round, and a temperature control flap that does not close properly. The flap is operated by a cable whose sheath can slip out of its lock. Check the flap's movement and the cable adjustment first.
How can I tell a water valve or heater core leak?
A wet driver's-side footwell, a sticky windscreen and the smell of coolant in the cabin point to a leak in the water valve or the heater core hose connections. The water valve is electric and shuts off the coolant to the heater core when the temperature is set to the lowest. It does not regulate temperature.
Why does the heater blower fuse blow?
If the fuse blows only at a certain blower speed, the fault is usually in the wiring and not in the switch itself. Go through the wires with a multimeter. Sometimes the cause is a broken wire in the bundle of wires in the driver's footwell running against the sill trim box.
Does the E30 have a heater auxiliary water pump?
It varies. The auxiliary water pump is an option that not all cars have, and engine versions differ from each other. If the pump is broken or seized, the heater core does not warm up, especially at idle. You can check that it is turning by feeling it with your hand.